344 
Having microscopically examined the dust again and again, I 
ignited it upon platinum to destroy any organic matter which might 
be present, and thereafter found the filaments, the flat plates, and 
the amorphous accretions of glass quite unchanged. 
No pyroxene, augite, or magnetite, such as have elsewhere been 
observed in volcanic dust, was present ; it may be assumed that, if 
at first mingled with the glass, those heavier minerals had been 
dropped during the long voyage of more than ten thousand miles of 
space and more than four months of time. 
The capacity of fine volcanic glass to float in the air to considera- 
ble distances being a well-established phenomenon, my examination 
claims no greater novelty or interest than what may be due to the 
actual finding of such glass at so great distance from the point of 
its ejection. : 
In this case two separate ejections seem to be indicated, for on 
-several evenings I observed a second and fainter glow after the 
original and stronger glow had entirely disappeared. A higher 
stratum of finer particles doubtless reflected the sunlight from the 
greater altitude after the sun had set at the lower elevation of the 
principal dust stratum. 
Early in February, 1884, the ship 7. &. Ridgeway arrived at 
Philadelphia from Manila by the Strait of Sunda. On February 
12, I visited that ship, and read on her log-book that at to P.M., 
October 27, 1883, in south latitude 7° 57’ and east longitude 100° 
54 (about five hundred miles W. S. W. from Krakatoa), she en- 
countered a vast field of floating pumice, through which she sailed 
until 7 a.m., October 29. So abundant was this pumice that the 
ship’s speed was reduced from nine knots when she entered it to two 
knots at 6 p.M., October 28; several hours after that time her speed 
gradually increased, as the pumice became less dense, from two 
knots to eight, and finally, when she cleared it, to her normal nine 
knots. No volcanic ash had fallen upon the ship, as she arrived too 
late upon the scene. 
Some of this pumice I took directly from the hands of the mate 
and steward, who had collected it from the sea and had kept it in 
their private lockers. It can scarcely be doubted that this pumice 
was ejected from Krakatoa. 
Now, on placing under the microscope small crumbs of that 
pumice and filaments picked out from its cavities, I recognized just 
such transparent flattish scraps and ragged accretions as were 
